Investigation of the Performance of V-cut Turbines for Stirring Shear-thinning Fluids in a Cylindrical Vessel

Abstract

The impeller design is the most crucial parameter to enhance the performance of stirred tanks. The cut in the impeller blade is a new technique to save the energy of impellers in mixing vessels without increasing the mixing time or reducing the product quality. In this paper, the new technique of cut is applied for a disc turbine rotating in an unbaffled cylindrical tank. Effects of the V-cut shape are highlighted. Non-Newtonian shear-thinning fluids are considered for the three flow regimes (laminar, transient, and turbulent). Effects of the number of blades on the flow patterns, pumping rate (Nq) and power consumption (Np) are explored. From the obtained results, a recirculation loop of flow is observed at the tip of each blade for impellers with less than three blades. These recirculation loops disappear with the increased number of blades. Under laminar flow conditions, the obtained results also revealed a decrease in power consumption and an increase in the discharge flow rate with the rise of Reynolds number. However, almost any changes were observed for these parameters (Np and Nq) under turbulent flow conditions.